Transcript Immune System

Immune System
Cells and Cell Products That
Protect the Body Against
Disease
T cells
B cells
Properties of the Immune Response
A. Specificity: Unique response
against each each invader
B. Memory: Increased response at
next invasion
C. Discrimination: Ability to
distinguish “self” from “non-self”
Applying Your Knowledge
1. Specificity
2. Memory
3. Discrimination between
Self and Non-self
Which property of the immune response:
A. keeps you from developing chicken pox a
second time? (Assume you had a severe
case at age six.)
B. helps you successfully recover from a cold?
C. causes you to reject a donated organ?
Sources and Transport of Immune System Cells
•
Sites of immune
cell production or
maturation
•
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•
bone marrow
spleen
thymus
tonsils
Circulation
– lymphatic system
•
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lymph vessels
lymph nodes
– bloodstream
Cells of the
Immune System
T cells carry out
cell-cell
interactions
B cells produce
antibodies that
bind to antigens
on the surface of
the invader
Macrophages
engulf invaders
and provide
signals for other
immune system
cells
• Surround invader
with plasma
membrane and
bring it into cell
(phagocytosis)
• Display antigen on
surface by making
a complex with
MHC protein
Activities of
Macrophages
MHC= major histocompatibility complex,
70 genes that code for cell surface proteins
B Cells Fight Against
Viruses and Bacteria
• Each B cell carries a unique antibody on its
surface
• When antigen on surface of invader binds to
antibody on B cell, the B cell divides and
gives rise to two types of cells
--plasma cell: actively secretes antibody
into bloodstream
--memory B cell: responds on second
invasion
Primary
Response: initial
activation of
immune system
and destruction
of invader
Memory Cells and
the Immune Response
Secondary
Response: faster
and stronger
activation of
immune system
due to memory
cells
Antibody Structure
Antibody has 2 heavy chains and 2 light chains.
Each chain has variable (V) and constant (C) region.
Variable regions bind to antigen.
Constant regions bind to cells or other antibodies.
Gene for
constant region
Gene
of lightfor
chain
constant region
of heavy chain
Genes for
variable region
Genes
of light for
chain
variable region
of heavy chain
Recombination during
Construction of Antibody Genes
Antibodies Mark Invaders for Destruction
Phagocytosis by
a Macrophage
Applying Your Knowledge
1.
2.
3.
4.
Light Chain
Heavy Chain
Variable Region
Constant Region
1.
2.
3.
4.
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
A. Which part of the antibody binds to the
antigen? (choices on left)
B. Which type of protein structure is seen
in a functional antibody molecule?
(choices on right)
Classes of T Cells
1. Helper T cells: activate B
cells and cytotoxic T cells
2. Cytotoxic T cells: rupture
infected body cells or
cancer cells
Cytotoxic T cell
attacks a cancer cell
Cancer cell
T cell
Communication
Among Cells
1. Macrophage
engulfs
7. Dividing B cell invader
gives rise to
memory B cells
and plasma cells
2. Macrophage
displays
“processed”
antigen
6. Activated Helper
T cell stimulates
division of selected
B cell
4. Helper T Cell
binds to
Macrophage
3. Invader binds to
B cell that carries
antibody matching
the antigen
5. Macrophage
releases cytokines to
activate Helper T cell
Applying Your Knowledge
1.
2.
3.
4.
5.
Macrophage
Plasma Cell
Memory B Cell
Helper T Cell
Cytotoxic T Cell
Which immune system cell:
A. keeps you from developing chicken pox a
second time? (Assume you had a severe
case at age six.)
B. helps you successfully recover from a cold?
C. causes you to reject a donated organ?
Humoral and Cellular Immunity
Humoral
(Antibody-mediated)
Hay fever
Cellular
(T-cell mediated)
Reaction to poison ivy
Transfusion reactions
Tuberculin Test
Rh disease
Reaction to bee stings
Immunization
Graft (organ) rejection
Viral and Bacterial
infections
Cancer Prevention
Diseases of the Immune
System
A. Inherited Immune Deficiencies
eg. SCID: Severe Combined Immune Deficiency
B. AIDS: Acquired Immune Deficiency Syndrome
C. Autoimmune diseases
1. Scleroderma
2. Rheumatiod arthritis
D. Allergies
Allergies
Produces
antibodies with
unique constant
region (IgE)
Antigen
binds to B
cell and
activates it
Antigen
binds to
IgE on
mast cells
IgE
antibodies
bind to
mast cells
Mast cells
release
histamines
Envelope
Core
(lipid bilayer) Proteins
Reverse
Transcriptase
Viral RNA in
protein coat
HIV
Glycoproteins
Protein
Coat
Entry of HIV Retrovirus into Host Cell
DNA copy of
retroviral genome
Production of New Viral Particles
Contains more than
one protein product;
individual proteins
are separated by
protease
HIV Binds to CD4 and CCR5
Co-receptors on Helper T cells
Individuals that are homozygous for a deletion
mutation in the CCR5 gene are resistant to HIV infection.
HIV Destroys T cells
Use of ELISA to detect
Antibodies to HIV
ELISA = Enzyme-Linked
Immunosorbent Assay
Tests serum for the presence of
antibodies directed against HIV
ELISA Procedure
Substrate:
Salicylate
(colorless)
Product:
Oxidized
Salicylate
(brown)
Anti-IgG with
horseradish
peroxidase enzyme
Anti-HIV in serum
of infected person
No brown product
formed
Anti-IgG with enzyme
does not bind
No Anti-HIV in serum
of uninfected person
HIV antigen
Infected Person
Result
HIV antigen
Uninfected Person
Result
Instructions for ELISA
• Follow ALL directions on pages 90-101 of
workbook (summarized in these slides)
• Label the vertical side of a microtiter plate as
Rows 1, 2, 3, 4 so that there are three wells per
row.
• Add the antigen: Use a micropipettor and a
CLEAN tip to add 0.1 mL (100 uL) of HIV antigen
(viral antigens) to all wells.
• Incubate at room temperature for 5 minutes then
empty the wells with the “flip and bang” method.
• Wash the wells: Add PBS buffer with transfer
pipette, empty wells with “flip and bang” method.
Instructions for ELISA
• Add the test sera: (use clean tip for each)
– 100 uL PBS buffer to the three wells in row 1
(negative control).
– 100 uL of “+” (positive control: antibody to the
HIV antigen) to the three wells in row 2.
– 100 uL of Donor Serum 1 to the three wells in
row 3.
– 100 uL of Donor Serum 2 to the three wells in
row 4.
• Incubate at 37o (oven on side bench) for 15
minutes then empty the wells with the “flip and
bang” method.
• Wash the wells: Add PBS buffer with transfer
pipette, empty wells with “flip and bang” method.
Instructions for ELISA
• Add the 2o Ab: Place 100 uL of the anti-IgG
peroxidase conjugate in all 12 wells.
• Incubate at 37o (oven on side bench) for 15
minutes then empty the wells with the “flip and
bang” method.
• Wash the wells: Add PBS buffer with transfer
pipette, empty wells with “flip and bang” method.
• Add the substrate: Place 100 uL of the substrate
in all 12 wells.
• Incubate at 37o (oven on side bench) for 5
minutes.
• Evaluate the plate for color change